IS CELLOBIOSE OXIDASE FROM PHANEROCHAETE-CHRYSOSPORIUM A ONE-ELECTRONREDUCTASE

The heme domain of cellobiose oxidase (CBO) from Phanerochaete chrysos porium increases the rate of electron transfer to one-electron accepto rs. This conclusion was drawn from comparisons of the rates of reducti on of 3,5-t-butyl-o-benzoquinone, triiodide ion, cytochrome c and ferr icyanide by intact CBO, FAD fragment and CBO with the heme inactivated by cyanide. The oxidation of cellobiose produced hydrogen peroxide, b ut the enzyme disturbs peroxidase-based assays by reduction of the pro duct or by direct interaction with the peroxidase. CBO can also degrad e hydrogen peroxide in the presence of cellobiose. The 1,2,4,5-tetrame thoxybenzene cation radical was rapidly reduced by CBO.